In many surgical procedures, particularly orthopedic procedures, it has now become common to affix a prosthesis to a bone or joint structure for improving the strength, rigidity, and movement of the bone/joint structure. Although such prosthetic devices have been widely used, hip joints and knee joints are the most common examples of areas where prosthetic devices are used to reduce or eliminate pain and suffering that exists from typical leg movements.
As part of these operations, it has become common practice to secure the prosthesis to the bone or joint using a cement, formed by intermixing a powder and a liquid. Once intermixed, the two components must be thoroughly blended together to achieve the required consistency for the fully mixed cement, with the fully mixed cement then being loaded into a dispensing apparatus for placement in the desired area for affixing the prosthesis to the desired site.
In most applications, the two components forming the cement are mixed in a mixing vessel and, once fully mixed, are manually transferred from the mixing vessel to a dispensing member. Typically, devices such as caulking guns are employed, for dispensing the fully mixed cement to the precisely desired location of the patient. This process is extremely unpleasant for individuals mixing the cement, since the mixed cement contains an offensive, noxious odor. Furthermore, removal of the mixed cement from the mixing vessel into the caulking gun is cumbersome, time consuming, and has the potential for being mishandled and/or dropped.
Another problem typically encountered with prior art systems is the difficulty encountered with air being entrapped in the mixed cement. The presence of air pockets or air bubbles in the mixed cement is undesirable. Since it is important that the cement added to the bone area for affixing the prosthetic be virtually free of any entrapped air bubbles or air pockets, most prior art systems demand mixing of the powder and liquid under vacuum conditions. As a result, added limitations are incurred on the flexibility of the mixing vessel and the ability to mix the two-part cement mixture in any desired location.
Although attempts have been made to reduce or eliminate some of these prior art problems, no prior art systems has been developed which completely eliminates the requirement for vacuum or the requirement for two separate components for mixing and dispensing. At best, some prior art systems have enabled the mixing to be performed in one vessel which then is directly connected to a feeding system for enabling the mixed cement to be added to a holding tube for use with the dispensing caulking gun. However, a separate dispensing system is required and extra handling and exposure of the mixed cement to the surrounding personnel is required. Furthermore, care must be exercised during the transfer of the mixed cement to the dispenser, since air is frequently introduced into the cement during this transfer operation as well as the risk of dropping or spilling the material.
Therefore, it is a principal object of the present invention to provide a bone cement mixing and dispensing system which comprises a fully integrated, unitary structure which eliminates the requirement for independent transfer of the mixed cement to a dispensing member.
Another object of the present invention is to provide a unitary, integrated, mixing and dispensing system for bone cement having the characteristic features described above which is easy to use and is virtually fool-proof in its operation.
Another object of the present invention is to provide a unitary, integrated, mixing and dispensing system for bone cement having the characteristic features described above which provides intermixed bone cement virtually devoid of entrapped air pockets or air bubbles while eliminating the need for mixing under vacuum but enabling vacuum to be used, if desired.
Another object of the present invention is to provide a unitary, integrated, mixing and dispensing system for bone cement having the characteristic features described above which is easily employed by any individual, free from unwanted odors and product handling difficulties.
Other and more specific objects will in part be obvious and will in part appear hereinafter.